Compositions for use in golf balls

ABSTRACT

Golf balls comprising thermoplastic, thermoset, castable, or millable elastomer compositions are disclosed. These elastomer compositions comprise the reaction product of an isocyanate, a moisture-resistant polyamine, and an amine- or hydroxyl-terminated curing agent, and can be used in any one or more portions of the golf balls, such as the inner core, outer core, intermediate layer, inner cover, and/or outer cover.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/014,503, filed Aug. 30, 2013, which is a continuation ofU.S. patent application Ser. No. 12/762,410, filed Apr. 19, 2010, nowU.S. Pat. No. 8,524,852, the entire disclosures of which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to golf balls containing atleast one layer made from a polyurethane, polyurethane-urea, polyurea,or polyurea-urethane composition that is based on a moisture-resistantpolyol or polyamine. More particularly, the composition is produced froma reaction of polyisocyanate with a moisture-resistant polyol and curingagent, or from a reaction of polyisocyanate with a moisture-resistantpolyamine and curing agent. The composition may be used to form anylayer in the golf ball including, for example, an outer core,intermediate layer, inner cover, and/or outer cover. The resulting golfball has desirable playing performance properties including highresiliency, toughness, impact durability, moisture-resistance, and softfeel.

BACKGROUND OF THE INVENTION

Today, multi-piece solid golf balls are popular for several reasonsincluding new manufacturing methods, the availability and cost of rawmaterials, and the playing performance properties of such balls. Forexample, three-piece solid golf balls having an inner core and outercover with an intermediate layer disposed there between are commonlyused by both professional and recreational golfers. Many multi-pieceballs are designed to have an optimum combination of playing properties.Particularly, such balls are designed to have high durability andresiliency as well as a soft feel. The durability and toughness of theball protects it from being cut, torn, and otherwise damaged. Ballshaving a high resiliency tend to reach a high velocity when struck by agolf club. As a result, the ball tends to travel a greater distancewhich is particularly important for driver shots off the tee. Meanwhile,the soft feel of the ball provides the player with a more pleasantsensation when he/she strikes the ball with the club. The player sensesmore control over the ball as the club face makes impact. The soft feelof the ball's cover allows players to place a spin on the ball andbetter control its flight pattern which is particularly important forapproach shots near the green.

In conventional multi-piece golf balls, the inner core is made commonlyof a rubber material such as natural and synthetic rubbers, styrenebutadiene, polybutadiene, poly(cis-isoprene), poly(trans-isoprene), orhighly neutralized acid copolymers. Often, the intermediate layer ismade of an olefin-based ionomer resin that imparts some hardness to theball. These ionomer acid copolymers contain inter-chain ionic bondingand are generally made of an α-olefin such as ethylene and a vinylcomonomer having an acid group such as methacrylic, acrylic acid, ormaleic acid. Metal ions such as sodium, lithium, zinc, and magnesium areused to neutralize the acid groups in the copolymer. Commerciallyavailable olefin-based copolymer ionomer resins are used in differentindustries and include numerous resins sold under the trademarks,Surlyn® (available from DuPont) and Escor® and Iotek® (available fromExxonMobil), Amplify IO® (available from Dow Chemical) and Clarix®(available from A. Schulman). Olefin-based copolymer ionomer resins areavailable in various grades and identified based on the type of baseresin, molecular weight, and type of metal ion, amount of acid, degreeof neutralization, additives, and other properties. Finally, the outercover of conventional golf balls are made from a variety of materialsincluding olefin-based copolymer ionomers, polyamides, polyesters, andthermoplastic and thermoset polyurethane and polyurea elastomers.

In recent years, there has been substantial interest in using thermosetand thermoplastic polyurethanes and polyureas to make cover layers forthe golf balls. Polyurethane and polyurea golf ball covers are ofparticular interest because they can be formulated to provide the golfball with high resiliency and durability as well as a soft feel.Basically, polyurethane compositions contain urethane linkages formed byreacting an isocyanate group (—N═C═O) with a hydroxyl group (OH), andpolyurea compositions contain urea linkages formed by reacting anisocyanate group with an amine group (NH₂). Polyurethanes are producedby the reaction of a polyisocyanate with a polyol in the presence of acatalyst and other additives. Polyureas are produced by the reaction ofa polyisocyanate with a polyamine, optionally in the presence of acatalyst and other additives. The chain length of the prepolymer isextended by reacting it with a hydroxyl- or amine-terminated curingagent. Hybrid compositions containing urethane and urea linkages alsomay be produced. For example, a polyurethane/urea hybrid composition maybe produced when polyurethane prepolymer is reacted with anamine-terminated curing agent.

Golf balls made with polyurethane and polyurea materials are generallydescribed in the patent literature, for example, U.S. Pat. Nos.5,334,673; 5,484,870; 6,476,176; 6,506,851; 6,867,279; 6,958,379;6,960,630; 6,964,621; 7,041,769; 7,105,623; 7,131,915; and 7,186,777. Asdiscussed above, in general, isocyanate compounds with two or morefunctional groups are reacted with polyols or polyamines to form thepolyurethane or polyurea compositions. There are various known methodsfor making thermoplastic polyurethanes and polyureas. For example,Meltzer et al., U.S. Patent Application Publication No. US 2009/0192262describes a specific method for making hydrophobic thermoplasticpolyurethanes. According to the '262 Publication, a polyol, apolyisocyanate, and a linear diol chain extender containing 5 carbonatoms or 7 to 12 carbon atoms are required as the reactants. There is nodisclosure of isocyanate or polyol compounds containing acidic or ionicmoieties. The '262 Publication discloses that the thermoplasticpolyurethane compositions may be used for over-molding soft grips ontotools and kitchen utensils, and in adhesives and protective coatings.

Although many conventional golf balls containing polyurethane orpolyurea components or layers have good mechanical and playingproperties, there is a continuing need for improved polyurethane andpolyurea golf balls. The improved golf balls should have highresiliency, impact durability, and toughness as well as features thatmake the ball easy to play with, particularly a pleasant feel, softness,and the like. The present invention provides methods for making suchgolf balls and the resultant balls. The present invention relates tomulti-layered golf balls made from a composition comprising apolyurethane, polyurea, polyurethane-urea, or polyurea-urethane. Thecomposition may be used to form any layer in the golf ball structuresuch as, for example, inner core, outer core, intermediate layer, innercover, and/or outer cover. The golf balls made of the compositions ofthis invention are highly resilient and have good impact durability andtoughness. Moreover, the ball has a soft feel and optimum playingperformance properties.

SUMMARY OF THE INVENTION

In one embodiment, the present invention relates to multi-layered golfballs made from a composition comprising a thermoset polyurethane orpolyurethane-urea that is based on a moisture-resistant polyol. Thethermoset composition preferably has a cross-link density in the rangeof about 10 to about 300 mol/m³ and a Vicat softening temperature in therange of about 60° to about 180° C. More particularly, the compositionis formed from: i) an isocyanate compound, ii) a moisture-resistantpolyol having a weight average molecular weight in the range of 500 to10,000 grams per mole, and iii) a curing agent.

In another embodiment, the present invention relates to multi-layeredgolf balls made from a composition comprising a polyurea orpolyurea-urethane that is based on a moisture-resistant polyamine. Thecomposition preferably has a cross-link density in the range of about 10to about 300 mol/m³ and a Vicat softening temperature in the range ofabout 60° to about 180° C. More particularly, the composition is formedfrom: i) an isocyanate compound, ii) a moisture-resistant polyaminehaving a weight average molecular weight in the range of 500 to 10,000grams per mole, and iii) a curing agent.

Compositions of the present invention may be used to form any layer inthe golf ball structure such as for example, an inner core, outer core,intermediate layer, inner cover, and/or outer cover. The golf balls madeof the composition of this invention are highly resilient and have goodimpact durability and toughness. The composition provides the golf ballwith good moisture-resistance. Moreover, the ball's cover has a softfeel and the ball has optimum playing performance properties.

In one preferred embodiment, the ball includes a core which can be madeof polybutadiene, highly neutralized polymer, or other suitablematerial. The core preferably has a Shore C surface hardness in therange of about 50 to about 90. An intermediate layer comprising athermoplastic or thermoset composition surrounds the core. One exampleof a suitable thermoplastic composition that can be used to form theintermediate layer is an ethylene-based copolymer ionomer. A covercomprising the thermoset polyurethane or polyurethane-urea compositionof this invention surrounds the intermediate layer, and the cover has aShore C surface hardness in the range of about 60 to about 95. Thisthermoset cover composition is the reaction product of: i) an isocyanatecompound, ii) a moisture-resistant polyol having a weight averagemolecular weight in the range of 500 to 10,000 grams per mole, and iii)a curing agent selected from hydroxyl-terminated or amine-terminatedcuring agents, and mixtures thereof. The resulting thermoset compositionpreferably has a cross-link density in the range of about 10 to about300 mol/m³ and a Vicat softening temperature in the range of about 60°to about 180° C. In one preferred embodiment, the core has a diameter ofabout 1.26 to about 1.60 inches and surface hardness of about 30 toabout 65 Shore D; the intermediate layer has a thickness of about 0.015to about 0.120 inches and surface hardness of about 45 to about 75 ShoreD; and the cover layer has a thickness of about 0.015 to about 0.090inches and material hardness of about 40 to about 65 Shore D.

Different moisture-resistant polyols may be used. For instance, themoisture-resistant polyol may be the reaction product of dimer acid ordimer ester and a polyolefin diol, polybutadiene polyol, or polyisoprenediol. In one example, the polybutadiene polyol or polyisoprene diol arehydrogenated. In yet another version, a polyether-ester diol, which isthe reaction product of dimer acid or dimer ester and polyether diol, isused. A polycaprolactone-ester diol, which is the reaction product ofdimer acid or dimer ester and polycaprolactone diol, also may be used.The moisture-resistant polyol may be prepared by dimerizing unsaturatedaliphatic monocarboxylic acid or ester containing 10 to 60 carbon atomsfollowed by reacting it with a monomeric or polymeric diol. In onepreferred version, the moisture-resistant polyol is a branched polyesterpolyol containing 36 carbon atoms.

In another preferred embodiment, the ball includes a core having a ShoreC surface hardness in the range of about 60 to about 95. An intermediatelayer comprising a thermoplastic or thermoset composition surrounds thecore. One example of a suitable thermoplastic composition that can beused to form the intermediate layer is an ethylene-based copolymerionomer. A multi-layered cover with inner and outer cover layerscomprising the polyurethane or polyurethane-urea composition of thisinvention surrounds the intermediate layer, and the cover has a Shore Csurface hardness in the range of about 50 to about 90.

In another preferred embodiment, the ball includes a core which can bemade of polybutadiene, highly neutralized polymer, or other suitablematerial. The core preferably includes an inner core and outer corelayer, the inner core having a Shore C surface hardness in the range ofabout 50 to about 90, and the outer core layer having a Shore D surfacehardness in the range of about 50 to about 90. An intermediate layercomprising a thermoplastic or thermoset composition surrounds the core.One example of a suitable thermoplastic composition that can be used toform the intermediate layer is an olefin-based acid copolymer ionomer,and particularly an olefin-based acid copolymer ionomer having ahardness in the range of 30 to 90 Shore D. A cover comprising a polyureaor polyurea-urethane composition of the present invention surrounds theintermediate layer and has a Shore C surface hardness in the range ofabout 60 to about 95. The polyurea or polyurea-urethane composition isthe reaction product of: i) an isocyanate compound, ii) amoisture-resistant polyamine having a weight average molecular weight inthe range of 500 to 10,000 grams per mole, and iii) a curing agentselected from hydroxyl-terminated and amine-terminated curing agents,and mixtures thereof. The resulting composition preferably has across-link density in the range of about 10 to about 300 mol/m³ and aVicat softening temperature in the range of about 60° to about 180° C.In one preferred embodiment, the core has a diameter of about 1.26 toabout 1.60 inches and surface hardness of about 30 to about 65 Shore D;the intermediate layer has a thickness of about 0.015 to about 0.120inches and surface hardness of about 45 to about 75 Shore D; and thecover layer has a thickness of about 0.015 to about 0.090 inches andmaterial hardness of about 40 to about 65 Shore D. The ratio of thecover Shore C surface hardness to inner core Shore C surface hardness ispreferably in the range of 0.6 to 1.4. The cover layer preferably has amoisture vapor transmission rate between 3 grams·mm/m²·day to 4grams·mm/m²·day.

In another preferred embodiment, the ball includes a core which can bemade of polybutadiene, highly neutralized polymer, or other suitablematerial. The core is preferably a solid, single layer core having aShore C surface hardness in the range of about 50 to about 90. Anintermediate layer comprising a thermoplastic or thermoset compositionsurrounds the core. One example of a suitable thermoplastic compositionthat can be used to form the intermediate layer is an olefin-based acidcopolymer ionomer, and particularly an olefin-based acid copolymerionomer having a hardness in the range of 30 to 90 Shore D. A covercomprising a polyurea or polyurea-urethane composition of the presentinvention surrounds the intermediate layer and has a Shore C surfacehardness in the range of about 60 to about 95. The polyurea orpolyurea-urethane composition is the reaction product of: i) anisocyanate compound, ii) a moisture-resistant polyamine having a weightaverage molecular weight in the range of 500 to 10,000 grams per mole,and iii) a curing agent selected from hydroxyl-terminated oramine-terminated curing agents, and mixtures thereof. The resultingcomposition preferably has a cross-link density in the range of about 10to about 300 mol/m³ and a Vicat softening temperature in the range ofabout 60° to about 180° C. In one preferred embodiment, the core has adiameter of about 1.26 to about 1.60 inches and surface hardness ofabout 30 to about 65 Shore D; the intermediate layer has a thickness ofabout 0.015 to about 0.120 inches and surface hardness of about 45 toabout 75 Shore D; and the cover layer has a thickness of about 0.015 toabout 0.090 inches and material hardness of about 40 to about 65 ShoreD. The ratio of the cover Shore C surface hardness to core Shore Csurface hardness is preferably in the range of 0.6 to 1.4. The coverlayer preferably has a moisture vapor transmission rate between 3grams·mm/m²·day to 4 grams·mm/m²·day.

Preferably, the polyurethane, polyurea, polyurethane-urea, orpolyurea-urethane polymer composition has a Vicat softening temperatureof 60° to 180° C., and material Shore D hardness of about 30 to about75. The polyurethane, polyurea, polyurethane-urea, or polyurea-urethanecomposition is post cross-linked using a chemical or radiationcross-linking process. In one version, the reaction used to produce thepolyurethane, polyurea, polyurethane-urea, or polyurea-urethanecomposition is a one-step reaction. In a second version, the reactionused to produce the polyurethane, polyurea, polyurethane-urea, orpolyurea-urethane composition is a two-step reaction, wherein the firststep comprises reacting the isocyanate compound and moisture-resistantpolyol or polyamine to form a prepolymer and the second step comprisesreacting the prepolymer with the curing agent.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features that are characteristic of the present invention areset forth in the appended claims. However, the preferred embodiments ofthe invention, together with further objects and attendant advantages,are best understood by reference to the following detailed descriptionin connection with the accompanying drawings in which:

FIG. 1 is a front view of a dimpled golf ball made in accordance withthe present invention;

FIG. 2 is a cross-sectional view of a multi-layered (three-piece) golfball having an intermediate layer made of a composition in accordancewith the present invention;

FIG. 3 is a cross-sectional view of a multi-layered (four-piece) golfball having an outer core layer made of a composition in accordance withthe present invention;

FIG. 4 is a cross-sectional view of a multi-layered (four-piece) golfball having an inner cover layer made of a composition in accordancewith the present invention; and

FIG. 5 is a cross-sectional view of a multi-layered (five-piece) golfball having a multi-layered core, intermediate layer, and outer coverlayer made in accordance with the present invention.

DETAILED DESCRIPTION

The present invention relates generally to golf balls containing atleast one “layer” made from a polyurethane, polyurea, polyurethane-urea,or polyurea-urethane composition that is produced by a reaction of: i)an isocyanate compound, ii) a moisture-resistant polyol having anaverage molecular weight in the range of 500 to 10,000 grams per moleand a hydroxyl value in the range of 30 to 120 or a moisture-resistantpolyamine having an average molecular weight in the range of 500 to10,000 grams per mole, and iii) a curing agent selected fromhydroxyl-terminated and amine-terminated curing agents and mixturesthereof. The term, “layer” as used herein means generally any sphericalportion of a golf ball. The polyurethane, polyurea, polyurethane-urea,or polyurea-urethane composition of this invention may be used to formany layer in the golf ball structure including, but not limited to, anouter cover, inner cover, intermediate layer, and/or outer core layer.

Isocyanate Compounds

Any suitable isocyanate known in the art can be used to produce thecompositions in accordance with this invention. Such isocyanatesinclude, for example, aliphatic, cycloaliphatic, aromatic aliphatic,aromatic, any derivatives thereof, and combinations of these compoundshaving two or more isocyanate (—N═C═O) groups per molecule. Theisocyanates may be organic polyisocyanate-terminated prepolymers,isocyanate prepolymers having a low residual amount of unreactedisocyanate monomer (“low free” isocyanates), and mixtures thereof. Theisocyanate-containing reactable component also may include anyisocyanate-functional monomer, dimer, trimer, or polymeric adductthereof, prepolymer, quasi-prepolymer, or mixtures thereof.Isocyanate-functional compounds may include monoisocyanates orpolyisocyanates that include any isocyanate functionality of two ormore.

Preferred isocyanates include diisocyanates (having two NCO groups permolecule), biurets thereof, dimerized uretdiones thereof, trimerizedisocyanurates thereof, and polyfunctional isocyanates such as monomerictriisocyanates. Diisocyanates typically have the generic structure ofOCN—R—NCO. Exemplary diisocyanates include, but are not limited to,unsaturated isocyanates such as: p-phenylene diisocyanate (“PPDI,” i.e.,1,4-phenylene diisocyanate), m-phenylene diisocyanate (“MPDI,” i.e.,1,3-phenylene diisocyanate), o-phenylene diisocyanate (i.e.,1,2-phenylene diisocyanate), 4-chloro-1,3-phenylene diisocyanate,toluene diisocyanate (“TDI”), m-tetramethylxylene diisocyanate(“m-TMXDI”), p-tetramethylxylene diisocyanate (“p-TMXDI”), 1,2-, 1,3-,and 1,4-xylene diisocyanates, 2,2′-, 2,4′-, and 4,4′-biphenylenediisocyanates, 3,3′-dimethyl-4,4′-biphenylene diisocyanate (“TODI”),2,2′-, 2,4′-, and 4,4′-diphenylmethane diisocyanates (“MDI”),3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, carbodiimide-modifiedMDI, polyphenylene polymethylene polyisocyanate (“PMDI,” i.e., polymericMDI), 1,5-naphthalene diisocyanate (“NDI”), 1,5-tetrahydronaphththalenediisocyanate, anthracene diisocyanate, tetracene diisocyanate; andsaturated isocyanates such as: 1,4-tetramethylene diisocyanate,1,5-pentamethylene diisocyanate, 2-methyl-1,5-pentamethylenediisocyanate, 1,6-hexamethylene diisocyanate (“HDI”) and isomersthereof, 2,2,4- and 2,4,4-trimethylhexamethylene diisocyanates,1,7-heptamethylene diisocyanate and isomers thereof, 1,8-octamethylenediisocyanate and isomers thereof, 1,9-nonamethylene diisocyanate andisomers thereof, 1,10-decamethylene diisocyanate and isomers thereof,1,12-dodecane diisocyanate and isomer thereof, 1,3-cyclobutanediisocyanate, 1,2-, 1,3-, and 1,4-cyclohexane diisocyanates, 2,4- and2,6-methylcyclohexane diisocyanates, isophorone diisocyanate (“IPDI”),isocyanatomethylcyclohexane isocyanate, isocyanatoethylcyclohexaneisocyanate, 4,4′-dicyclohexylmethane diisocyanate (“H₁₂ MDI,” i.e.,bis(4-isocyanatocyclohexyl)-methane), and 2,4′- and 4,4′-dicyclohexanediisocyanates. Dimerized uretdiones of diisocyanates and polyisocyanatesinclude, for example, unsaturated isocyanates such as uretdiones oftoluene diisocyanates, uretdiones of diphenylmethane diisocyanates; andsaturated isocyanates such as uretdiones of hexamethylene diisocyanates.Trimerized isocyanurates of diisocyanates and polyisocyanates include,for example, unsaturated isocyanates such as trimers of diphenylmethanediisocyanate, trimers of tetramethylxylene diisocyanate, isocyanuratesof toluene diisocyanates; and saturated isocyanates such asisocyanurates of isophorone diisocyanate, isocyanurates of hexamethylenediisocyanate, isocyanurates of trimethyl-hexamethylene diisocyanates.Monomeric triisocyanates include, for example, unsaturated isocyanatessuch as 2,4,4′-diphenylene triisocyanate, 2,4,4′-diphenylmethanetriisocyanate, 4,4′,4″-triphenylmethane triisocyanate; and saturatedisocyanates such as: 1,3,5-cyclohexane triisocyanate.

Other suitable isocyanates include acid functionalized isocyanatescontaining acid groups such as, for example, carboxylic, sulfonic, orphosphoric acid groups. The acid content may be, for example, in therange of about 2.5 wt. % to about 25 wt. %, preferably about 5 to about20 wt. %, based on weight of polymer composition. Also, the acid groupsof the acid-functionalized isocyanates may be partially, highly, orfully neutralized using organic or inorganic cations to form ionomers.For example, the neutralization level may be from 10 to 80%, morepreferably 20 to 70%, and most preferably 30 to 50% forpartially-neutralized ionomers. In another embodiment, theneutralization level is from 80 to 100%, more preferably 90 to 100%, andmost preferably 95 to 100% for highly or fully-neutralized ionomers. Byincorporating acid or ionic groups into the backbone of the isocyanates,the properties of the resulting polyurethane or polyurea such asscuff/abrasion-resistance and resiliency can be enhanced.

Preferably, the isocyanate compound is selected from the groupconsisting of monomeric, oligomeric, or polymeric isophoronediisocyanate (IPDI); hexamethylene diisocyanate (HDI); 1,4-cyclohexyldiisocyanate (CHDI); 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI);4,4′-dicyclohexylmethane diisocyanate (4,4′-MDI); 4,4′-diphenylmethanediisocyanate (“MDI”); toluene diisocyanate (TDI); p-phenylenediisocyanate (PPDI); 1,5-naphthalene diisocyanate (“NDI”); xylenediisocyanate (“XDI”); and tetramethylxylene diisocyanate (TMXDI”); andmixtures thereof.

Polyol Compounds

As discussed above, a polyurethane composition is generally anelastomeric material that is the reaction product of isocyanate andhydroxyl components. There are many polyol compounds known in the art.Surprisingly, it has been found that a moisture-resistant polyol that isthe reaction of product of a dimer acid or dimer ester and a polyolefindiol, polybutadiene polyol, or polyisoprene diol is particularlyeffective and provides a polyurethane composition having manyadvantageous properties for purposes of this invention. For instance,because of the moisture-resistant polyols, the resulting polyurethanecompositions of this invention will tend to have greatermoisture-resistance than polyurethane compositions prepared from polyolsthat are not highly moisture-resistant. In a second preferredembodiment, the dimer acid or dimer ester is reacted with ahydrogentated polybutadiene or hydrogenated polyisoprene diol to producea moisture-resistant polyol that, in turn, can be reacted with theisocyanate compound to produce the polyurethane composition. Anotherpreferred moisture-resistant polyol that can be used in this inventionis a polyether-ester diol that is the reaction product of a dimer acidor dimer ester and a polyether diol. In yet another preferred version,the moisture-resistant polyol is a polycaprolactone-ester diol that isthe reaction product of a dimer acid and polycaprolactone diol.

Other suitable polyols include acid functionalized polyols containingacid groups such as, for example, carboxylic, sulfonic, or phosphoricacid groups. The acid content may be, for example, in the range of about2.5 wt. % to about 25 wt. %, preferably about 5 to about 20 wt. %, basedon weight of polymer composition. Also, the acid groups of theacid-functionalized polyols may be partially, highly, or fullyneutralized using organic or inorganic cations to form ionomers. Forexample, the neutralization level may be from 10 to 80%, more preferably20 to 70%, and most preferably 30 to 50% for partially-neutralizedionomers. In another embodiment, the neutralization level is from 80 to100%, more preferably 90 to 100%, and most preferably 95 to 100% forhighly or fully-neutralized ionomers. By incorporating acid or ionicgroups into the backbone of the polyols, the properties of the resultingpolyurethane such as tensile strength, impact durability, resiliency,and toughness can be enhanced. Mixtures of the above-describedmoisture-resistant polyols also can be used in accordance with thisinvention.

Dimer acids and dimer esters are commercially available and can be usedto prepare the moisture-resistant polyols of this invention. They arenormally prepared by dimerizing unsaturated long chain aliphaticmonocarboxylic acids, usually of 10 to 60 carbon atoms, or their esters(alkyl esters). This is followed by reacting the dimer acid or dimerester with a monomeric or polymeric polyol. Certain moisture-resistantpolyols are commercially available and can be used in accordance withthis invention. For example, Priplast™ polyester polyols, available fromUniqema of Gouda (The Netherlands) are branched C₃₆ moisture-resistantpolyols that can be used. The moisture-resistant polyol used insynthesizing the thermoset polyurethane of this invention typically willhave a weight average molecular weight in the range of about 500 toabout 10,000 grams per mole and preferably will have a hydroxyl value inthe range of 30 to 120 mg KOH/g (as measured in accordance with ASTME-222). The moisture-resistant polyols used in this invention have highhydrolytic resistance and tensile strength. Thus, they can be reactedwith isocyanate compounds and curing agents to produce polyurethanecompositions having ideal properties as discussed further below.Moreover, the moisture-resistant polyols have a highlymoisture-resistant backbone. Thus, the resulting polyurethanescompositions will tend to be more moisture-resistant than polyurethanesprepared from polyols that do not have a moisture-resistant backbone.

Suitable polyols are further disclosed, for example, in U.S. Pat. No.8,273,845 to Meltzer et al.

Polyamine Compounds

As discussed above, a polyurea composition is generally an elastomericmaterial that is the reaction product of isocyanate and aminecomponents. There are many polyamine compounds known in the art. In aparticular embodiment, the polyamine is a dimer diamine made bynitrilation of the fatty acid e.g. with ammonia, followed byhydrogenation, as further disclosed, for example, in U.S. PatentApplication Publication No. 2011/0105661, the entire disclosure of whichis hereby incorporated herein by reference.

Dimer acids and dimer esters are commercially available and can be usedto prepare the moisture-resistant polyamines of this invention. They arenormally prepared by dimerizing unsaturated long chain aliphaticmonocarboxylic acids, usually of 10 to 60 carbon atoms, or their esters(alkyl esters). Certain moisture-resistant polyamines are commerciallyavailable and can be used in accordance with this invention. In aparticular embodiment, the moisture-resistant polyamine is selected fromPriamine™ C₃₆ dimer diamines, commercially available from CRODA. Themoisture-resistant polyamine used in synthesizing the polyurea of thisinvention typically will have a weight average molecular weight in therange of about 500 to about 10,000 grams per mole. Themoisture-resistant polyamines used in this invention have highhydrolytic resistance and tensile strength. Thus, they can be reactedwith isocyanate compounds and curing agents to produce polyureacompositions having ideal properties as discussed further below.Moreover, the moisture-resistant polyamines have a highlymoisture-resistant backbone. Thus, the resulting polyurea compositionswill tend to be more moisture-resistant than polyureas prepared frompolyamines that do not have a moisture-resistant backbone.

Manufacturing Processes

There are two basic techniques that can be used to make the compositionsof the present invention: a) one-shot technique, and b) prepolymertechnique. In the one-shot technique, the isocyanate, polyol orpolyamine, and hydroxyl and/or amine-terminated curing agent are reactedin one step. The prepolymer technique involves a first reaction betweenthe isocyanate and polyol or polyamine compounds to produce apolyurethane or polyurea prepolymer, and a subsequent reaction betweenthe prepolymer and hydroxyl and/or amine-terminated curing agent. As aresult of the reaction between the isocyanate and polyol or polyaminecompounds, there will be some unreacted NCO groups in the prepolymer.The prepolymer should have less than 14% unreacted NCO groups.Preferably, the prepolymer has no greater than 8.5% unreacted NCOgroups, more preferably from 2.5% to 8%, and most preferably from 5.0%to 8.0% unreacted NCO groups. As the weight percent of unreactedisocyanate groups increases, the hardness of the composition alsogenerally increases.

Either the one-shot or prepolymer method may be employed to produce thecompositions of the invention. In one embodiment, the one-shot method isused, wherein the isocyanate compound is added to a reaction vessel andthen a curative mixture comprising the polyol or polyamine and curingagent is added to the reaction vessel. The components are mixed togetherso that the molar ratio of isocyanate compound to total polyol orpolyamine and curing agent compounds is in the range of about 1.01:1.00to about 1.10:1.00. Preferably, the molar ratio is greater than1.05:1.00. For example, the molar ratio can be in the range of 1.07:1.00to 1.10:1.00. In general, the prepolymer technique is preferred becauseit provides better control of the chemical reaction. The prepolymermethod provides a more homogeneous mixture resulting in a moreconsistent polymer composition. In one embodiment, the prepolymer methodis used, wherein the isocyanate and polyol or polyamine compounds arereacted to produce a polyurethane or polyurea prepolymer. This isfollowed by a reaction between the prepolymer and curing agent to formthe final polymer composition. In the prepolymer method, the prepolymeris mixed with the curing agent so that the molar ratio of isocyanategroups to hydroxyl groups (and/or amine groups) is in the range of about1.01:1.00 to about 1.10:1.00. Preferably, the molar ratio is greaterthan 1.05:1.00. For example, the molar ratio can be in the range of1.07:1.00 to 1.10:1.00.

In one embodiment, the resulting prepolymer is a polyurethane prepolymercontaining urethane linkages having the following general structure:

where x is the chain length, i.e., about 1 or greater, and R and R₁ arestraight chain or branched hydrocarbon chain having about 1 to about 20carbons.

In another embodiment, the resulting prepolymer is a polyurea prepolymercontaining urea linkages having the following general structure:

where x is the chain length, i.e., about 1 or greater, and R and R₁ arestraight chain or branched hydrocarbon chain having about 1 to about 20carbons.

In general, polyurethanes and polyureas are classified as eitherthermoplastic or thermosetting materials. Thermoplastic polyurethanesand polyureas have some cross-linking, but it is primarily throughhydrogen bonding or other physical mechanism. Because of their lowerlevel of cross-linking, thermoplastic polyurethanes and polyureas arerelatively flexible. The cross-linking bonds in thermoplasticpolyurethanes and polyureas can be reversibly broken by increasingtemperature such as during molding or extrusion. That is, thethermoplastic material softens when exposed to heat and returns to itsoriginal condition when cooled. On the other hand, thermosetpolyurethanes and polyureas become irreversibly set when they are cured.The cross-linking bonds are irreversibly set and are not broken whenexposed to heat. Thus, thermoset polyurethanes and polyureas, whichtypically have a high level of cross-linking, are relatively rigid.

Chain-Extending of Prepolymer

As discussed above, either the one-shot or prepolymer method may be usedto form the polyurethane or polyurea composition. In the prepolymermethod, the prepolymer can be chain-extended by reacting it with asingle curing agent or blend of curing agents. In general, theprepolymer can be reacted with hydroxyl-terminated curing agents,amine-terminated curing agents, or mixtures thereof. The curing agentsextend the chain length of the prepolymer and build-up its molecularweight. In one embodiment, the compositions of the present invention arecastable thermoset polyurethanes and polyureas. In another embodiment,the compositions of the present invention are thermoplasticpolyurethanes and polyureas.

A catalyst may be employed to promote the reaction between theisocyanate and polyol or polyamine compound for producing the prepolymeror between prepolymer and curing agent during the chain-extending step.In a particular embodiment, the catalyst is added to the reactantsbefore producing the prepolymer. Suitable catalysts include, but are notlimited to, bismuth catalyst; zinc octoate; stannous octoate; tincatalysts such as bis-butyltin dilaurate, bis-butyltin diacetate,stannous octoate; tin (II) chloride, tin (IV) chloride, bis-butyltindimethoxide, dimethyl-bis[1-oxonedecyl)oxy]stannane, di-n-octyltinbis-isooctyl mercaptoacetate; amine catalysts such astriethylenediamine, triethylamine, and tributylamine; organic acids suchas oleic acid and acetic acid; delayed catalysts; and mixtures thereof.The catalyst is preferably added in an amount sufficient to catalyze thereaction of the components in the reactive mixture. In one embodiment,the catalyst is present in an amount from about 0.001 percent to about 1percent, and preferably 0.1 to 0.5 percent, by weight of thecomposition.

The hydroxyl-terminated chain-extending (curing) agents are preferablyselected from the group consisting of ethylene glycol; diethyleneglycol; polyethylene glycol; propylene glycol; 2-methyl-1,3-propanediol;2-methyl-1,4-butanediol; monoethanolamine; diethanolamine;triethanolamine; monoisopropanolamine; diisopropanolamine; dipropyleneglycol; 1,2-butanediol; 1,3-butanediol; 1,4-butanediol; 2,3-butanediol;2,3-dimethyl-2,3-butanediol; trimethylolpropane; cyclohexyldimethylol;triisopropanolamine; N,N,N′,N′-tetra-(2-hydroxypropyl)-ethylene diamine;diethylene glycol bis-(aminopropyl) ether; 1,5-pentanediol;1,6-hexanediol; 1,3-bis-(2-hydroxyethoxy)cyclohexane;1,4-cyclohexyldimethylol; 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]cyclohexane; 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}cyclohexane; trimethylolpropane; polytetramethylene etherglycol (PTMEG), preferably having a molecular weight from about 250 toabout 3900; and mixtures thereof. In addition, the followinghydroxyl-terminated curing agents may be used: 1,7-heptanediol,1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and1,12-dodecanediol. However, it is not required that only linearhydroxyl-terminated curing agents containing 1 to 12 carbon atoms beused in the method of this invention. For instance, linearhydroxyl-terminated curing agents containing greater than 12 carbonatoms such as tetradecanoic (C₁₄) diols, hexadecanoic (C₁₆) diols, andoctadecanoic (C₁₈) diols may be used. In addition, alkyl or arylsubstituted alkane diols containing greater than 12 carbon atoms may beused. As discussed above, the properties of the polyurethane compositiondepend in significant part upon the components or building blocks usedto make the composition, particularly the polyisocyanates,moisture-resistant polyols, and curing agents of this invention. Theabove-mentioned hydroxyl-terminated curing agents may be used to makepolyurethane compositions having enhanced tensile strength, impactdurability, scuff/abrasion-resistance, resiliency, as well asmoisture-resistance.

Suitable amine-terminated chain-extending (curing) agents that can beused in chain-extending the prepolymer of this invention include, butare not limited to, unsaturated diamines such as4,4′-diamino-diphenylmethane (i.e., 4,4′-methylene-dianiline or “MDA”),m-phenylenediamine, p-phenylenediamine, 1,2- or1,4-bis(sec-butylamino)benzene, 3,5-diethyl-(2,4- or 2,6-)toluenediamine or “DETDA”, 3,5-dimethylthio-(2,4- or2,6-)toluenediamine, 3,5-diethylthio-(2,4- or 2,6-)toluenediamine,3,3′-dimethyl-4,4′-diamino-diphenylmethane,3,3′-diethyl-5,5′-dimethyl4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(2-ethyl-6-methyl-benezeneamine)),3,3′-dichloro-4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(2-chloroaniline) or “MOCA”),3,3′,5,5′-tetraethyl-4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(2,6-diethylaniline),2,2′-dichloro-3,3′,5,5′-tetraethyl-4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(3-chloro-2,6-diethyleneaniline) or “MCDEA”),3,3′-diethyl-5,5′-dichloro-4,4′-diamino-diphenylmethane, or “MDEA”),3,3′-dichloro-2,2′,6,6′-tetraethyl-4,4′-diamino-diphenylmethane,3,3′-dichloro-4,4′-diamino-diphenylmethane,4,4′-methylene-bis(2,3-dichloroaniline) (i.e.,2,2′,3,3′-tetrachloro-4,4′-diamino-diphenylmethane or “MDCA”),4,4′-bis(sec-butylamino)-diphenylmethane,N,N′-dialkylamino-diphenylmethane,trimethyleneglycol-di(p-aminobenzoate),polyethyleneglycol-di(p-aminobenzoate),polytetramethyleneglycol-di(p-aminobenzoate); saturated diamines such asethylene diamine, 1,3-propylene diamine, 2-methyl-pentamethylenediamine, hexamethylene diamine, 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine, imino-bis(propylamine), imido-bis(propylamine),methylimino-bis(propylamine) (i.e.,N-(3-aminopropyl)-N-methyl-1,3-propanediamine),1,4-bis(3-aminopropoxy)butane (i.e.,3,3′-[1,4-butanediylbis-(oxy)bis]-1-propanamine),diethyleneglycol-bis(propylamine) (i.e.,diethyleneglycol-di(aminopropyl)ether),4,7,10-trioxatridecane-1,13-diamine, 1-methyl-2,6-diamino-cyclohexane,1,4-diamino-cyclohexane, poly(oxyethylene-oxypropylene)diamines, 1,3- or1,4-bis(methylamino)-cyclohexane, isophorone diamine, 1,2- or1,4-bis(sec-butylamino)-cyclohexane, N,N′-diisopropyl-isophoronediamine, 4,4′-diamino-dicyclohexylmethane,3,3′-dimethyl-4,4′-diamino-dicyclohexylmethane,3,3′-dichloro-4,4′-diamino-dicyclohexylmethane,N,N′-dialkylamino-dicyclohexylmethane, polyoxyethylene diamines,3,3′-diethyl-5,5′-dimethyl-4,4′-diamino-dicyclohexylmethane,polyoxypropylene diamines,3,3′-diethyl-5,5′-dichloro-4,4′-diamino-dicyclohexylmethane,polytetramethylene ether diamines,3,3′,5,5′-tetraethyl-4,4′-diamino-dicyclohexylmethane (i.e.,4,4′-methylene-bis(2,6-diethylaminocyclohexane)),3,3′-dichloro-4,4′-diamino-dicyclohexylmethane,2,2′-dichloro-3,3′,5,5′-tetraethyl-4,4′-diamino-dicyclohexylmethane,(ethylene oxide)-capped polyoxypropylene ether diamines,2,2′,3,3′-tetrachloro-4,4′-diamino-dicyclohexylmethane,4,4′-bis(sec-butylamino)-dicyclohexylmethane; triamines such asdiethylene triamine, dipropylene triamine, (propylene oxide)-basedtriamines (i.e., polyoxypropylene triamines),N-(2-aminoethyl)-1,3-propylenediamine (i.e., N₃-amine), glycerin-basedtriamines, (all saturated); tetramines such asN,N′-bis(3-aminopropyl)ethylene diamine (i.e., N₄-amine) (bothsaturated), triethylene tetramine; and other polyamines such astetraethylene pentamine (also saturated). The amine curing agents usedas chain extenders normally have a cyclic structure and a low molecularweight (250 or less). More preferably, the amine-terminated curing agentcan be selected from the group consisting of: 1,3-propane diamine,1,4-butane diamine, 1,5-pentane diamine, 1,6-hexane diamine, 1,7-heptanediamine, 1,8-octane diamine, 1,9-nonane diamine, 1,10-decane diamine,1,11-undecane diamine, and 1,12-dodecane diamine,polymethylene-di-p-aminobenzoates,polyethyleneglycol-bis(4-aminobenzoates), polytetramethyleneetherglycol-di-p-aminobenzoate, polypropyleneglycol-di-p-aminobenzoate,and mixtures thereof.

In yet other embodiment, a polyamide curing agent having multiple aminogroups capable of reacting with the isocyanate groups and at least oneamide group can be used. Polyamine polyamides can be used, wherein thepolyamide chain is formed from condensation polymerization reaction ofpolyacid (including polyacid telechelic) and polyamine (includingpolyamine telechelic), with an equivalent ratio of polyamine to polyacidbeing greater than 1, such as about 1.1-5 or about 2. Mixtures ofpolyacid and polyamine can be, for example, hexamethylene diammoniumadipate, hexamethylenediammonium terephthalate, or tetramethylenediammonium adipate. Alternatively, the polyamide chain can be formedpartially or essentially from ring-opening polymerization of cyclicamides such as caprolactam. The polyamide chain can also be formedpartially or essentially from polymerization of amino acid, includingthose that structurally correspond to the cyclic amides. The polyamidechain can comprise multiple segments formed from the same or differentpolyacids, polyamines, cyclic amides, and/or amino acids, non-limitingexamples of which are disclosed herein. Suitable starting materials alsoinclude polyacid polymers, polyamine telechelics, and amino acidpolymers. At least one polyacid, polyamine, cyclic amide, or amino acidhaving Mw of at least about 200, such as at least about 400, or at leastabout 1,000 can be used to form the backbone. A blend of at least twopolyacids and/or a blend of at least two polyamines can be used, whereinone has a molecular weight greater than the other. The polyacid orpolyamine of smaller molecular weight can contribute to hard segments inthe polyamine polyamide, which may improve shear resistance of theresulting elastomer. For example, the first polyacid/polyamine can havea molecular weight of less than 2,000, and the second polyacid/polyaminecan have a molecular weight of 2,000 or greater. In one example, apolyamine blend can comprise a first polyamine having a Mw of 1,000 orless, such as JEFFAMINE. 400 (Mw of about 400), and a second polyaminehaving a Mw of 1,500 or more, such as JEFFAMINE 2000 (Mw of about2,000). The backbone of the polyamine polyamide can have about 1-100amide linkages, such as about 2-50, or about 2-20. Polyamine polyamidescan be linear, branched, star-shaped, hyper-branched or dendritic (suchas amine-terminated hyper-branched quinoxaline-amide polymers of U.S.Pat. No. 6,642,347, the disclosure of which is incorporated herein byreference).

When a polyurethane prepolymer is reacted with hydroxyl-terminatedcuring agents during the chain-extending step, as described above, theresulting composition is essentially a pure polyurethane composition. Onthe other hand, when the polyurethane prepolymer is reacted with anamine-terminated curing agent during the chain-extending step, anyexcess isocyanate groups in the prepolymer will react with the aminegroups in the curing agent and create urea linkages having the followinggeneral structure:

where x is the chain length, i.e., about 1 or greater, and R and R₁ arestraight chain or branched hydrocarbon chain having about 1 to about 20carbons.

Likewise, when a polyurea prepolymer is reacted with amine-terminatedcuring agents during the chain-extending step, as described above, theresulting composition is essentially a pure polyurea composition. On theother hand, when the polyurea prepolymer is reacted with ahydroxyl-terminated curing agent during the chain-extending step, anyexcess isocyanate groups in the prepolymer will react with the hydroxylgroups in the curing agent and create urethane linkages.

This chain-extending step, which occurs when the prepolymer is reactedwith hydroxyl-terminated curing agents, amine-terminated curing agents,or mixtures thereof, builds-up the molecular weight and extends thechain length of the prepolymer. As stated above, when a polyurethaneprepolymer is reacted with hydroxyl-terminated curing agents, apolyurethane composition having urethane linkages is produced, and whena polyurea prepolymer is reacted with amine-terminated curing agents, apolyurea composition having urea linkages is produced. When apolyurethane prepolymer is reacted with amine-terminated curing agents,a polyurethane-urea hybrid composition having urethane and urea linkagesis produced, and when a polyurea prepolymer is reacted withhydroxyl-terminated curing agents, a polyurea-urethane hybridcomposition having urea and urethane linkages is produced.Polyurethane-urea and polyurea-urethane hybrid compositions are distinctfrom pure polyurethane and polyurea compositions. The concentration ofurethane and urea linkages in the hybrid composition may vary. Ingeneral, hybrid compositions may contain a mixture of about 10 to 90 wt% urethane and about 90% to 10 wt % urea linkages. The resultingpolyurethanes, polyureas, polyurethane-ureas, and polyurea-urethaneshave elastomeric properties based on phase separation of the soft andhard segments. The soft segments, which are formed from the polyol andpolyamine reactants, are generally flexible and mobile, while the hardsegments, which are formed from the isocyanate and chain extenders, aregenerally stiff and immobile.

Compositions of the present invention may have many advantageousphysical properties and features. For example, compositions of thepresent invention generally have a flexural modulus (as measured inaccordance with ASTM D-790) of about 10 to about 150 kpsi, preferably 15to 125 kpsi, and more preferably 18 to 90 kpsi. In addition, thecompositions typically have an elongation at break (as measured inaccordance with ASTM D-638) of about 100 to about 950%, preferably 125to 750%, and more preferably 200 to 650%; a tensile strength at break(as measured in accordance with ASTM D-638) of about 1 to about 6 kpsi,preferably 2 to 5 kpsi, and more preferably 3 to 4.5 kpsi; and a notchedIzod strength (as measured in accordance with ASTM D-256) of at least10, preferably 15 to no break, and more preferably 20 to no break asmeasured at 23° C. The Vicat softening temperature (as measured inaccordance with ASTM D-1525-70) of the compositions is preferably about60° to 180° C., and more preferably 75 to 150° C. Lastly, the density(as measured in accordance with ASTM D-792) of the compositions is about1.01 to about 1.60, preferably 1.02 to 1.50, and more preferably 1.03 to1.30. It is important that the cover material of the golf ball hassufficient heat-resistance. If the cover material softens or melts, thedimples on the ball's surface will change shape and harmfully affect theaerodynamic properties of the ball.

In a particular embodiment, compositions of the present invention have across-link density in the range of about 10 to about 300 mol/m³ (molesof effective network chains per cubic meter) and preferably about 15 toabout 250 mol/m³. Compositions of the present invention have goodmechanical strength and toughness because of their good cross-linkingnetwork. By adjusting the cross-link density of the composition, thescuff-resistance, toughness, and durability of the resulting golf ballcover can be improved. It is believed that the increase in cross-linkingdensity may be due at least in part to the allophanate linkages formedin the reaction of the isocyanate, moisture-resistant polyol orpolyamine, and curing agent. Cross-link density is defined as moles ofeffective network chains per cubic meter and computed from swellingparameters of the networks and may be measured in accordance with theprocedures described in V. Sekkar, S. Gopalakrishnan, and K. AmbikaDevi, Studies on Allophonate-Urethane Networks Based on HydroxylTerminated Polybutadiene: Effect of Isocyanate Type on the NetworkCharacteristics, European Polymer Journal 39, (2003) (pp. 1281-1290).The test specimens were paced in toluene for 48 hrs at ambientconditions. The specimens were removed from the solvent and weighedafter gently wiping off the solvent from the surface of the specimen.Subsequently, the solvent absorbed was driven off by placing the swollenspecimen in a vacuum oven at 100° C. for 2 hr and the weight of thedeswollen (dried) specimen was determined. From the weights of theswollen and deswollen specimens, and the densities of the polymer andthe solvent, the volume fraction of the polymer in the swollen specimenwas calculated. The crosslink densities of the polymer networks wereobtained using Flory-Rhener equation.

Golf Ball Construction

Compositions of the present invention may be used with any type of ballconstruction. Such golf ball designs include, for example, single-piece,two-piece, three-piece, four-piece, and five-piece designs so long as atleast one layer comprises a polyurethane, polyurea, polyurethane-urea,or polyurea-urethane composition prepared in accordance with thisinvention. The core, intermediate, and/or cover portions of the ball maybe single or multi-layered.

Core

The cores in the golf balls of this invention may be solid, semi-solid,hollow, fluid-filled, or powder-filled. Typically, the cores are solidand made from rubber compositions containing a base rubber, free-radicalinitiator agent, cross-linking co-agent, and fillers. The base rubbermay be selected, for example, from polybutadiene rubber, polyisoprenerubber, natural rubber, ethylene-propylene rubber, ethylene-propylenediene rubber, styrene-butadiene rubber, and combinations of two or morethereof. A preferred base rubber is polybutadiene. Another preferredbase rubber is polybutadiene optionally mixed with one or moreelastomers such as polyisoprene rubber, natural rubber, ethylenepropylene rubber, ethylene propylene diene rubber, styrene-butadienerubber, polystyrene elastomers, polyethylene elastomers, polyurethaneelastomers, polyurea elastomers, acrylate rubbers, polyoctenamers,metallocene-catalyzed elastomers, and plastomers. As discussed furtherbelow, highly neutralized acid copolymers (HNPs), as known in the art,also can be used to form the core layer.

The base rubber typically is mixed with at least one reactivecross-linking co-agent to enhance the hardness of the rubbercomposition. Suitable co-agents include, but are not limited to,unsaturated carboxylic acids and unsaturated vinyl compounds. Apreferred unsaturated vinyl is trimethylolpropane trimethacrylate. Therubber composition is cured using a conventional curing process.Suitable curing processes include, for example, peroxide curing, sulfurcuring, high-energy radiation, and combinations thereof. In oneembodiment, the base rubber is peroxide cured. Organic peroxidessuitable as free-radical initiators include, for example, dicumylperoxide; n-butyl-4,4-di(t-butylperoxy) valerate;1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane;2,5-dimethyl-2,5-di(t-butylperoxy) hexane; di-t-butyl peroxide;di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide;2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3;di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoylperoxide; t-butyl hydroperoxide; and combinations thereof. Cross-linkingagents are used to cross-link at least a portion of the polymer chainsin the composition. Suitable cross-linking agents include, for example,metal salts of unsaturated carboxylic acids having from 3 to 8 carbonatoms; unsaturated vinyl compounds and polyfunctional monomers (forexample, trimethylolpropane trimethacrylate); phenylene bismaleimide;and combinations thereof. In a particular embodiment, the cross-linkingagent is selected from zinc salts of acrylates, diacrylates,methacrylates, and dimethacrylates. In another particular embodiment,the cross-linking agent is zinc diacrylate (“ZDA”). Commerciallyavailable zinc diacrylates include those selected from RocklandReact-Rite and Sartomer.

The rubber compositions also may contain “soft and fast” agents such asa halogenated organosulfur, organic disulfide, or inorganic disulfidecompounds. Particularly suitable halogenated organosulfur compoundsinclude, but are not limited to, halogenated thiophenols. Preferredorganic sulfur compounds include, but not limited to,pentachlorothiophenol (“PCTP”) and a salt of PCTP. A preferred salt ofPCTP is ZnPCTP. A suitable PCTP is sold by the Struktol Company (Stow,Ohio) under the tradename, A95. ZnPCTP is commercially available fromEchinaChem (San Francisco, Calif.). These compounds also may function ascis-to-trans catalysts to convert some cis-1, 4 bonds in thepolybutadiene to trans-1, 4 bonds. Antioxidants also may be added to therubber compositions to prevent the breakdown of the elastomers. Otheringredients such as accelerators (for example, tetra methylthiuram),processing aids, dyes and pigments, wetting agents, surfactants,plasticizers, as well as other additives known in the art may be addedto the rubber composition. The core may be formed by mixing and formingthe rubber composition using conventional techniques. These cores can beused to make finished golf balls by surrounding the core with outer corelayer(s), intermediate layer(s), and/or cover materials as discussedfurther below. In another embodiment, the cores can be formed usinghighly neutralized polymer (HNP) compositions as disclosed in U.S. Pat.Nos. 6,756,436, 7,030,192, 7,402,629, and 7,517,289. The cores from thehighly neturalized polymer compositions can be further cross-linkedusing any free-radical initiation sources including radiation sourcessuch as gamma or electron beam as well as chemical sources such asperoxides and the like. The core may contain sections having the samehardness or different hardness levels. That is, there can be uniformhardness throughout the different sections of the core or there can behardness gradients across the layers. For example, in single cores,there may be a hard-to-soft gradient (a “positive” gradient) from thesurface of the core to the geometric center of the core. In otherinstances, the there may be a soft-to-hard gradient (a “negative”gradient) or zero hardness gradient from the core's surface to thecore's center. For dual core golf balls, the inner core layer may have asurface hardness that is less than the geometric center hardness todefine a first “negative” gradient. As discussed above, an outer corelayer may be formed around the inner core layer, and the outer corelayer may have an outer surface hardness less than its inner surfacehardness to define a second “negative” gradient. In other versions, thehardness gradients from surface to center may be hard-to-soft(“positive”), or soft-to-hard (“negative”), or a combination of bothgradients. In still other versions the hardness gradients from surfaceto center may be “zero” (that is, the hardness values are substantiallythe same.) Methods for making cores having positive, negative, and zerohardness gradients are known in the art as described in, for example,U.S. Pat. Nos. 7,537,530; 7,537,529; 7,427,242; and 7,410,429, thedisclosures of which are hereby incorporated by reference.

Golf balls made in accordance with this invention can be of any size,although the USGA requires that golf balls used in competition have adiameter of at least 1.68 inches and a weight of no greater than 1.62ounces. For play outside of USGA competition, the golf balls can havesmaller diameters and be heavier. For example, the diameter of the golfball may be in the range of about 1.68 to about 1.80 inches. In FIG. 1,one version of a golf ball that can be made in accordance with thisinvention is generally indicated at (10). Various patterns and geometricshapes of dimples (11) can be used to modify the aerodynamic propertiesof the golf ball (10). The dimples (11) can be arranged on the surfaceof the ball (10) using any suitable method known in the art. In oneembodiment, as shown in FIG. 2, the core is a single-piece having anoutside diameter of about 1.00 to about 1.65 inches. Preferably, thesingle-piece core has a diameter of about 1.50 to about 1.64 inches. Thecore generally makes up a substantial portion of the ball, for example,the core may constitute at least about 90% of the ball. The hardness ofthe core may vary depending upon desired properties of the ball. Ingeneral, core hardness is in the range of about 50 to about 90 Shore Cand more preferably in the range of about 55 to about 75 Shore C. Thecompression of the core is generally in the range of about 30 to about110 and more preferably in the range of about 50 to about 100. In asecond embodiment, as shown in FIG. 3, the core is made up of twopieces. The inner core (22) may be made of a rubber or other suitablecomposition as described above, while the outer core layer (24) may bemade of the polyurethane composition of this invention. In a preferredversion, the outer core layer has a thickness in the range of about0.030 to about 0.070 inches and a Shore D surface hardness in the rangeof about 50 to about 90 and more preferably in the range of about 55 toabout 75 Shore D.

Intermediate and Cover Layers

The golf balls of this invention preferably include at least oneintermediate layer. As used herein, the term, “intermediate layer” meansa layer of the ball disposed between the core and cover. Theintermediate layer may be considered an outer core layer or inner coverlayer or any other layer disposed between the inner core and outer coverof the ball. The intermediate layer also may be referred to as a casingor mantle layer. The intermediate layer preferably has water vaporbarrier properties to prevent moisture from penetrating into the rubbercore. The ball may include one or more intermediate layers disposedbetween the inner core and outer cover.

Compositions of the present invention can be used to make the innercore, outer core, intermediate layer, inner cover, and/or outer cover.In some instances, a traditional thermoplastic or thermosettingcomposition may be used to make one layer, and the polyurethane,polyurea, polyurethane-urea or polyurea-urethane composition of thepresent invention may be used to make a different layer of the golf balldepending upon the desired ball construction playing performanceproperties. If a conventional thermoplastic or thermosetting compositionis used, then a wide variety of thermoplastic or thermosetting materialscan be employed. These materials include for example, olefin-basedcopolymer ionomer resins (for example, Surlyn® ionomer resins and DuPontHPF® 1000 and HPF® 2000, commercially available from E. I. du Pont deNemours and Company; Iotek® ionomers, commercially available fromExxonMobil Chemical Company; Amplify® IO ionomers of ethylene acrylicacid copolymers, commercially available from The Dow Chemical Company;and Clarix® ionomer resins, commercially available from A. SchulmanInc.); polyurethanes; polyureas; copolymers and hybrids of polyurethaneand polyurea; polyethylene, including, for example, low densitypolyethylene, linear low density polyethylene, and high densitypolyethylene; polypropylene; rubber-toughened olefin polymers; acidcopolymers, for example, poly(meth)acrylic acid, which do not becomepart of an ionomeric copolymer; plastomers; flexomers;styrene/butadiene/styrene block copolymers;styrene/ethylene-butylene/styrene block copolymers; dynamicallyvulcanized elastomers; copolymers of ethylene and vinyl acetates;copolymers of ethylene and methyl acrylates; polyvinyl chloride resins;polyamides, poly(amide-ester) elastomers, and graft copolymers ofionomer and polyamide including, for example, Pebax® thermoplasticpolyether block amides, commercially available from Arkema Inc;cross-linked trans-polyisoprene and blends thereof; polyester-basedthermoplastic elastomers, such as Hytrel®, commercially available fromE. I. du Pont de Nemours and Company; polyurethane-based thermoplasticelastomers, such as Elastollan®, commercially available from BASF;synthetic or natural vulcanized rubber; and combinations thereof.

Compositions of the present invention optionally contain additives,including, but not limited to, activators such as calcium or magnesiumoxide; fatty acids such as stearic acid and salts thereof; fillers andreinforcing agents such as organic or inorganic particles, for example,clays, talc, calcium, magnesium carbonate, silica, aluminum silicateszeolites, powdered metals, and organic or inorganic fibers, plasticizerssuch as dialkyl esters of dicarboxylic acids; surfactants; softeners;tackifiers; waxes; ultraviolet (UV) light absorbers and stabilizers;antioxidants; optical brighteners; whitening agents such as titaniumdioxide and zinc oxide; dyes and pigments; processing aids; releaseagents; and wetting agents.

Compositions of the present invention may be blended with non-ionomericand olefin-based ionomeric polymers to form the composition that will beused to make the golf ball layer. Examples of non-ionomeric polymersinclude vinyl resins, polyolefins including those produced using asingle-site catalyst or a metallocene catalyst, polyurethanes,polyureas, polyamides, polyphenylenes, polycarbonates, polyesters,polyacrylates, engineering thermoplastics, and the like. The blend maycontain about 10 to about 90% by weight of the inventive polyurethane,polyurea, polyurethane-urea, or polyurea-urethane and about 90 to about10% by weight of the non-ionomeric polymer. Particularly, the blend maycontain a lower concentration of the inventive composition in the amountof 10%, 20%, 30%, 40%, or 50% and an upper concentration of theinventive composition in the amount of 60%, 70%, 80%, or 90%.Conversely, the concentration of non-ionomeric polymer may be relativelyhigh (60%, 70%, 80%, or 90%) or relatively low (10%, 20%, 30%, 40%, or50%).

Suitable olefin-based ionomers, such as ethylene-based copolymers,normally include an unsaturated carboxylic acid, such as methacrylicacid, acrylic acid, or maleic acid. Other possible carboxylic acidgroups include, for example, crotonic, maleic, fumaric, and itaconicacid. “Low acid” and “high acid” olefin-based ionomers, as well asblends of such ionomers, may be used. In general, low acid ionomers areconsidered to be those containing 16 wt. % or less of carboxylic acid,whereas high acid ionomers are considered to be those containing greaterthan 16 wt. % of carboxylic acid. The acidic group in the olefin-basedionic copolymer is partially or totally neutralized with metal ions suchas zinc, sodium, lithium, magnesium, potassium, calcium, manganese,nickel, chromium, copper, or a combination thereof. For example,ionomeric resins having carboxylic acid groups that are neutralized fromabout 10 percent to about 100 percent may be used. In one embodiment,the acid groups are partially neutralized. That is, the neutralizationlevel is from 10 to 80%, more preferably 20 to 70%, and most preferably30 to 50%. In another embodiment, the acid groups are highly or fullyneutralized. That is, the neutralization level is from 80 to 100%, morepreferably 90 to 100%, and most preferably 95 to 100%. The blend maycontain about 10 to about 90% by weight of the polyurethane and about 90to about 10% by weight of a partially, highly, or fully-neutralizedolefin-based ionomeric copolymer. Particularly, the blend may contain alower concentration of the inventive composition in the amount of 10%,20%, 30%, 40%, or 50% and an upper concentration of the inventivecomposition in the amount of 60%, 70%, 80%, or 90%. Conversely, theconcentration of olefin-based ionomer may be relatively high (60%, 70%,80%, or 90%) or relatively low (10%, 20%, 30%, 40%, or 50%). Theabove-mentioned blends may contain one or more suitable compatibilizerssuch as glycidyl acrylate or glycidyl methacrylate or maleic anhydridecontaining-polymers.

Golf Ball Dimensions and Properties

As discussed above, the polyurethane, polyurea, polyurethane-urea, andpolyurea-urethane compositions of the present invention may be used withany type of ball construction known in the art. Such golf ball designsinclude, for example, two-piece, three-piece, four-piece, and five-piecedesigns with single or multi-layered cores, intermediate and coverportions. The thickness and diameter of the different layers along withproperties such as hardness and compression may vary depending upon thedesired playing performance properties of the golf ball such as initialvelocity, spin control, and feel.

Referring to FIG. 2, a three-piece golf ball (12) that can be made inaccordance with this invention is illustrated. In this version, the ball(12) includes a solid core (14), an intermediate casing layer (16) andcover layer (18) made of the polyurethane, polyurea, polyurethane-urea,or polyurea-urethane composition. The core (14) is made of polybutadienerubber or other suitable material as described above and preferably hasa diameter in the range of about 1.30 to about 1.60 inches. Theintermediate layer (16) is made of a thermoplastic or thermosetcomposition as described above. For example, the intermediate layer (16)may be formed from a compound selected from the group consisting ofolefin-based ionomer copolymers; polyesters; polyester-ether elastomers;polyester-ester elastomers; polyamides; polyamide-ether elastomers, andpolyamide-ester elastomers; polyurethanes, polyureas, andpolyurethane-polyurea hybrids; and mixtures thereof. The range ofthickness for the intermediate layer (16) may vary, but it generally hasa thickness of about 0.015 to about 0.070 inches, preferably about 0.020to about 0.050 inches, and more preferably about 0.025 to about 0.040inches. The intermediate layer (16) preferably has a Shore D surfacehardness of 45 to 75, preferably 55 to 70, and most preferably 60 to 65.The thickness of the cover layer (18) may vary, but it is generally inthe range of about 0.015 to about 0.090 inches and more preferably 0.020to about 0.040 inches.

In one preferred version of a three-piece golf ball, the core has afirst Shore C surface hardness of C₁ in the range of about 50 to 90 andthe cover layer has a second Shore D surface hardness of C₂ in the rangeof about 60 to 95. The ratio of C₂ to C₁ is in the range of about 0.6 to1.4. It should be understood the three-piece golf ball constructionshown in FIG. 2 is for illustrative purposes only and not meant to berestrictive. Other three-piece constructions can be made per thisinvention. For example, the intermediate layer (16) may be made of acomposition of the present invention and the cover layer (18) may bemade of a conventional thermoset or thermoplastic composition. Inanother embodiment, the intermediate and cover layers each may be formedfrom a composition of the present invention. Different additives may beincorporated into the resins, and the layers may have similar ordifferent hardness levels. In order to make a visible distinctionbetween the layers, various colorants, dyes, pigments, and the like canbe added to the respective resins.

In FIG. 3, a four-piece golf ball (20) having a multi-layered core isillustrated. The multi-layered core includes an inner core (22) andouter core layer (24). The inner core (22) may be made of a first rubbermaterial, for example, polybutadiene, or highly neutralized polymer(HNP) and the outer core layer (24) may be made of a composition of thepresent invention. The golf ball further includes an intermediate casinglayer (26) and cover layer (28), which may have the same thicknessdimensions as described above. Conventional thermoplastic or thermosetresins such as olefin-based ionomeric copolymers, polyamides,polyesters, polycarbonates, polyolefins, polyurethanes, and polyureas asdescribed above can be used to make the casing layer (26) and/or coverlayer (28). In such multi-layered cores, the inner core (22) preferablyhas a diameter of about 0.50 to about 1.30 inches, more preferably 1.00to 1.15 inches, and may be relatively soft (that is, it may have acompression of less than about 30.) Meanwhile, the encapsulating outercore layer (24) generally has a thickness of about 0.030 to about 0.070inches, preferably 0.035 to 0.065 inches and may be relatively hard(compression of about 70 or greater.) That is, the two-piece core, whichis made up of the inner core (22) and outer core layer (24), preferablyhas a total diameter of about 1.50 to about 1.64 inches, more preferably1.510 to 1.620 inches, and a compression of about 80 to about 115, morepreferably 85 to 110.

In FIG. 3, the illustrated four-piece golf ball is not meant to belimiting. Other four-piece constructions can be made per this invention.For example, the intermediate casing layer (26) and/or cover layer (28)may be made of the same or different compositions of the presentinvention. Different additives may be incorporated into the resins, andthe layers may have similar or different hardness levels. In order tomake a visible distinction between the layers, various colorants, dyes,pigments, and the like can be added to the respective resins.

Turning to FIG. 4, a four-piece golf ball (30) having a multi-layeredcover is shown. The ball (30) includes a solid, rubber center (33), anouter core layer (34), and multi-layered cover constituting an innercover layer (31) and outer cover layer (32). The solid rubber center(33) preferably has a diameter of about 0.50 to about 1.30 inches, andmore preferably 1.00 to 1.15 inches, while the surrounding outer corelayer (34) preferably has a thickness of about 0.030 to about 0.070inches, and more preferably 0.035 to 0.065 inches. In this version, theinner cover layer (31) is made of a conventional thermoplastic orthermosetting resin and the outer cover layer (32) is made of acomposition of the present invention. The inner cover layer (31)preferably has a thickness of about 0.020 to about 0.050 inches andShore C surface hardness of about 60 to about 95. The inner cover (31)may be made of an ionomer resin or any other suitable inner covermaterial as described above. The outer cover layer (32), which surroundsthe inner cover layer (31), is preferably made of a composition of thepresent invention. The outer cover layer (32) preferably has a thicknessin the range of about 0.020 to about 0.035 inches and a Shore C surfacehardness in the range of about 50 to about 90. The four-piece golf ballconstruction shown in FIG. 4 is but one example and other four-piececonstructions can be made in accordance with this invention. Forinstance, in another version, the inner cover layer (31) may be made ofa composition of the present invention. The inner and outer cover layersmay be of different hardness levels. In one preferred embodiment, theinner cover has a greater hardness than the outer cover.

In FIG. 5, a five-piece golf ball (40) having a cover with three-layersis shown. The ball includes a solid, rubber center (41), an outer corelayer (44), and multi-layered cover constituting an inner cover layer(46), intermediate cover layer (48) and outer cover layer (50). In thisversion, the inner and intermediate cover layers (46, 48) are made ofconventional thermoplastic or thermosetting resins and the outer coverlayer (50) is made of a composition of the present invention. The innercover layer (46) preferably has a Shore C surface hardness of about 60to about 95. The intermediate cover (48) preferably has a Shore Csurface hardness of about 30 to about 50. The outer cover layer (50)preferably has a Shore C surface hardness of about 60 to about 95. Thatis, in one preferred embodiment, the intermediate cover layer (48) has aShore C surface hardness that is softer than both the inner cover layer(46) and outer cover layer (50).

As noted above, the golf ball constructions shown in FIGS. 1-5 are forillustrative purposes only and are not meant to be restrictive. A widevariety of golf ball constructions may be made in accordance with thepresent invention depending upon the desired properties of the ball solong as at least one layer contains the polyurethane composition of thisinvention.

Preferably, the overall diameter of the core and all intermediate layersis about 80 percent to about 98 percent of the overall diameter of thefinished ball. The core may have a diameter ranging from about 0.50inches to about 1.65 inches. In one embodiment, the diameter of the coreis about 1.20 inches to about 1.63 inches. For example, if a two-pieceball having a core and polyurethane, polyurea, polyurethane-urea, orpolyurea-urethane cover of the present invention is made, the core mayhave a diameter ranging from about 1.50 inches to about 1.62 inches. Thecore may further include a moisture-resistant surface to preventmoisture from penetrating there in. When the core includes an inner corelayer (center) and an outer core layer, the inner core layer ispreferably about 0.50 inches or greater and the outer core layerpreferably has a thickness of about 0.10 inches or greater. For example,when a multi-layer core is made, the center may have a diameter rangingfrom about 0.5 inches to about 1.30 inches and the outer core layer mayhave a diameter ranging from about 0.12 inches to about 0.5 inches. Thepolyurethane, polyurea, polyurethane-urea, or polyurea-urethane cover ofthis invention has a thickness to provide sufficient strength, goodperformance characteristics, and durability. In one embodiment, thecover thickness is from about 0.150 inches to about 0.090 inches,preferably about 0.070 inches or less. For example, when a two-pieceball according to invention is made, the cover may have a thicknessranging from about 0.030 inches to about 0.090 inches. In anotherinstance, when a three-piece ball is made, the thickness of the covermay be about 0.020 to 0.060 inches. Likewise, the range of thicknessesfor the intermediate layer may vary, because the intermediate layer maybe used in many different constructions and more than one intermediatelayer may be included in the ball. For example, the intermediate layermay be used as an outer core layer, an inner cover layer, and/or amoisture/vapor barrier layer. In general, the intermediate layer mayhave a thickness of about 0.120 inches or less. In general, thethickness of the intermediate layer is about 0.015 to about 0.120 inchesand preferably about 0.020 to about 0.060 inches. In one embodiment, thethickness of the intermediate layer is from about 0.015 inches to about0.100 inches.

The hardness of the golf ball (or subassembly such as the core) may varydepending upon the ball construction and desired performance properties.The test methods for measuring surface and material hardness aredescribed in further detail below. In general, surface or materialhardness refers to the firmness of the surface or material. The relativehardness levels of the core layer, intermediate layer(s), and coverlayer are primary factors in determining distance performance and spinrate of the ball. As a general rule, when the ball has a relatively softcover, the initial spin rate of the ball is relatively high and when theball has a relatively hard cover, the initial spin rate of the ball isrelatively low. Furthermore, in general, when the ball contains arelatively soft core, the resulting spin rate of the ball is relativelylow. The compressive force acting on the ball is less when the cover iscompressed by the club face against a relatively soft core. The clubface is not able to fully interface with the ball and thus the initialspin rate on the ball is lower. On the other hand, when the ballcontains a relatively hard core, the resulting spin rate of the ball isrelatively high. The club face is able to more fully interface with theball and thus the initial spin rate of the ball. The surface hardness ofa golf ball layer (or other spherical surface) is obtained from theaverage of a number of measurements taken from opposing hemispheres,taking care to avoid making measurements on the parting line of the coreor on surface defects such as holes or protrusions. In general, the CORof the ball will increase as the hardness of the ball is increased. Thetest methods for measuring surface and material hardness are describedin further detail below.

As discussed above, in one version of the golf ball of the presentinvention, the core preferably has a first surface hardness (C₁) in therange of about 50 to about 95 Shore C, more preferably about 55 to about85 Shore C, and most preferably about 60 to about 75 Shore C. Meanwhile,the cover layer preferably has a second surface hardness (C₂) in therange of about 65 to about 95 Shore C, more preferably about 65 to about90 Shore C, and most preferably about 70 to about 85 Shore C. And, theratio of C₂ to C₁ is in the range of 0.6 to 1.4.

In yet another embodiment, the hardness of the core (C₁) is in the rangeof about is about 55 to about 95 Shore C and more preferably about 60 toabout 90 Shore C. Meanwhile, the cover layer preferably has a secondsurface hardness (C₂) in the range of about 50 to about 95 Shore C andmore preferably about 60 to about 85 Shore C. And, the ratio of C₂ to C₁is in the range of 0.5 to 1.5.

The intermediate layer(s) may also vary in hardness. In one embodiment,the hardness of the intermediate layer is in the range of about 30 toabout 90 Shore D, preferably about 80 Shore D or less, and morepreferably about 70 Shore D or less. For example, when an intermediatelayer is formed from a composition of the present invention, thehardness of the intermediate layer may be about 65 Shore D or less,preferably ranging from about 35 to about 60 Shore D. In yet anotherembodiment, the hardness of the intermediate layer is about 50 Shore Dor greater, preferably about 55 Shore D or greater. In one embodiment,the intermediate layer hardness is from about 55 to about 65 Shore D.

There are several other physical properties of the golf ball that affectthe ball's playing performance. For example, the compression of the corecan affect the ball's spin rate off the driver as well as the “feel” ofthe ball as the club face makes impact with the ball. In general, ballswith relatively low compression values have a softer feel. As disclosedin Jeff Dalton's Compression by Any Other Name, Science and Golf IV,Proceedings of the World Scientific Congress of Golf (Eric Thain ed.,Routledge, 2002) (“J. Dalton”) several different methods can be used tomeasure compression including Atti compression, Riehle compression,load/deflection measurements at a variety of fixed loads and offsets,and effective modulus. The test methods for measuring compression inaccordance with the present invention are described in further detailbelow.

The “coefficient of restitution” or “COR” of a golf ball is also anotherimportant property and this refers to the ratio of a ball's reboundvelocity to its initial incoming velocity when the ball is fired out ofan air cannon into a rigid vertical plate. The COR for a golf ball iswritten as a decimal value between zero and one. A golf ball may havedifferent COR values at different initial velocities. The United StatesGolf Association (USGA) sets limits on the initial velocity of the ballso one objective of golf ball manufacturers is to maximize the COR underthese conditions. Balls with a higher rebound velocity have a higher CORvalue. Such golf balls rebound faster, retain more total energy whenstruck with a club, and have longer flight distance. In general, the CORof the ball will increase as the hardness of the ball is increased. Thetest methods for measuring COR are described in further detail below.

The golf balls of the present invention preferably have a “coefficientof restitution” (“COR”) of at least 0.750 and more preferably at least0.800 and compression of from about 70 to about 110, preferably from 90to 100.

The moisture vapor transmission rate (MVTR) of the layers in the golfball also is significant in golf ball design and construction. Asdiscussed above, the inner core (or center) helps provide resiliency tothe golf ball. As the core absorbs water, it tends to lose itsresiliency. The compression and COR of the ball may be reducedsignificantly if a large amount of water vapor permeates into the core.Layers of the golf balls, which are made of a polyurethane, polyurea,polyurethane-urea, or polyurea-urethane composition of the presentinvention, help minimize moisture penetration into the core. Preferably,the moisture vapor barrier layer has a thickness of 0.002 to 0.010inches, and a moisture vapor transmission rate of less than about 4.0grams·mm/m²·day, more preferably less than 3 grams·mm/m²·day, and mostpreferably less than 1.0 grams·mm/m²·day, particularly 0.5 to 1.0grams·mm/m²·day. The moisture vapor transmission rate is defined as themass of moisture vapor that diffuses into a material of a giventhickness per unit area per unit time. The test methods for measuringMVTR are described in further detail below.

Methods of Constructing Golf Ball Layers

The golf balls of the invention may be formed using a variety ofapplication techniques such as compression molding, flip molding,injection molding, retractable pin injection molding, reaction injectionmolding (RIM), liquid injection molding (LIM), casting, vacuum forming,powder coating, flow coating, spin coating, dipping, spraying, and thelike. Conventionally, compression molding and injection molding areapplied to thermoplastic materials, whereas RIM, liquid injectionmolding, and casting are employed on thermoset materials. These andother manufacturing methods are disclosed in U.S. Pat. Nos. 6,207,784and 5,484,870, the disclosures of which are hereby incorporated byreference. The cores of the golf balls of the invention may be formed byany suitable method known to those of ordinary skill in art. When thecores are formed from a thermoset material, compression molding is aparticularly suitable method of forming the core. On the other hand, thecores may be injection molded when the cores are formed using athermoplastic material.

More particularly, compositions of the present invention used to form athermoset cover or other layer of the golf ball are castable, reactiveliquids that can be applied over the golf ball subassembly (for example,core and overlying casing layer) using any suitable applicationtechnique spraying, dipping, spin coating, or flow coating methods whichare known in the art. In a particular embodiment, the composition of thepresent invention is of a liquid nature so as to make it possible to beapplied as a thin outer cover layer to the golf ball. For example, inone version of the casting method, the polyurethane or polyurea mixtureis dispensed into the cavity of an upper mold member. This firstmold-half has a hemispherical structure. Then, the cavity of acorresponding lower mold member is filled with the mixture. This secondmold-half also has a hemispherical structure. The cavities are typicallyheated beforehand. A ball cup holds the golf ball subassembly (core andoverlying casing layer) under vacuum. After the mixture in the firstmold-half has reached a semi-gelled or gelled sate, the pressure isremoved and the golf ball is lowered into the upper mold-half containingthe mixture. Then, the first mold-half is inverted and mated with thesecond mold-half containing mixture which also has reached a semi-gelledor gelled state. The mixtures, contained in the mold members that aremated together, form the golf ball cover. The mated first and secondmold-halves containing the mixture and golf ball center may be nextheated so that the mixture cures and hardens. Then, the golf ball isremoved from the mold and heated and cooled accordingly.

The intermediate layer and/or cover layer may also be formed using anysuitable method known to those of ordinary skill in the art. Forexample, an intermediate layer may be formed by blow molding orretractable pin molding and covered with a dimpled cover layer formed byinjection molding, compression molding, casting, vacuum forming, powdercoating, and the like. The use of various dimple patterns and profilesprovides a relatively effective way to modify the aerodynamiccharacteristics of a golf ball. As such, the manner in which the dimplesare arranged on the surface of the ball can be by any available method.For instance, the ball may have an icosahedron-based pattern, such asdescribed in U.S. Pat. No. 4,560,168, or an octahedral-based dimplepatterns as described in U.S. Pat. No. 4,960,281. Furthermore, theresultant golf balls prepared according to the invention typically willhave dimple coverage greater than about 60 percent, preferably greaterthan about 65 percent, and more preferably greater than about 70percent.

Golf Ball Post-Cross-Linking

The components in the golf balls of this invention may be cross-linkedby a variety of chemical and irradiation methods. For example, peroxidesor sulfur-based agents can be used to induce cross-linking of thepolymer chains. High-energy radiation, which is capable of generatingfree radicals, also may be used to cross-link the composition.Preferably, compositions of the present invention demonstrate anincrease in Shore D surface hardness of at least 2.5% upon being treatedwith chemical and/or irradiation methods to induce cross-linking. Morepreferably, the increase in Shore D surface hardness is in the range ofabout 2.5 to 20%. Ordinarily, thermoset compositions of the presentinvention have a relatively high amount of cross-linking in theirpolymer chains. When these thermoset compositions, along with the othercomponents in the golf ball, undergo a post cross-linking process, thereshould be additional cross-linking. The resulting golf ball will haveincreased hardness and toughness, but there will be no substantial lossin physical properties such as cut/tear-resistance;scuff/wear-resistance; or playing performance such as the soft feel andshot control of the ball. That is, even though the post cross-linkingprocess generates a ball having higher hardness, the cover of the balldoes not become brittle and there is no sacrifice of other physicalproperties. The ball covers maintain their high durability andresiliency as well as soft feel. It is believed that this increase inhardness while maintaining the other desirable properties is due to thebuilding blocks used to make the thermoset composition, particularly thepolyisocyanates, moisture-resistant polyols and polyamines, and curingagents of this invention.

Examples of suitable radiation sources include electron beams,ultra-violet (UV), gamma, X-ray, and infrared rays, heat, andcombinations thereof. Organic peroxides that can be used as free-radicalinitiators include, for example, dicumyl peroxide;n-butyl-4,4-di(t-butylperoxy) valerate;1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane;2,5-dimethyl-2,5-di(t-butylperoxy) hexane; di-t-butyl peroxide;di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide;2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3;di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoylperoxide; t-butyl hydroperoxide; and combinations thereof. The peroxidefree-radical initiators are generally present in compositions of thepresent invention in an amount within the range of 0.05 to 15 parts byweight per 100 parts of the base composition.

Cross-linking agents having an average functionality greater than 2.0can be added to the composition. For example, the cross-linking agentcan be added to the mixture of the isocyanate compound,moisture-resistant polyol or polyamine, and chain extender. Suitablecross-linking agents include, for example, metal salts of unsaturatedcarboxylic acids having from 3 to 8 carbon atoms; unsaturated vinylcompounds and polyfunctional monomers (for example, trimethylolpropanetrimethacrylate (TMP and pentaerythritol)); phenylene bismaleimide; andcombinations thereof. Particularly suitable metal salts include, forexample, one or more metal salts of acrylates, diacrylates,methacrylates, and dimethacrylates, wherein the metal is selected frommagnesium, calcium, zinc, aluminum, lithium, and nickel. In a particularembodiment, the cross-linking agent is selected from zinc salts ofacrylates, diacrylates (ZDA), methacrylates, and dimethacrylates. Thecross-linking agent typically is included in the base composition in anamount within the range of 1 to 70 parts.

The composition may further contain one or more photoinitiators that canbe activated by actinic radiation and initiate free radicalcross-linking. Suitable photoinitiators include, for example, aromaticketone compounds such as benzophenones, in combination with tertiaryamines, alkylbenzophenones, 4,4′-bis(dimethylamino)benzophenone(Michler's ketone), anthrone and halogenated benzophenones or mixturesof said types. Other photoinitiators, such as benzoin and itsderivatives, benzyl ketals, acylphosphine oxides, for example,2,4,6-tri-methylbenzoyldiphenylphosphine oxide, bisacylophosphineoxides, phenylglyoxylic acid esters, camphorquinone,.α-aminoalkylphenones, .α,α-dialkoxyacetophenones,1-[4-(phenylthio)phenyl]octane-1,2-dione-2-(O-benzoyloxime) andα-hydroxyalkylphenones, are suitable. The photoinitiator typically isincluded in the base composition in an amount within the range of 0.1 to10 weight percent.

As noted above, high energy radiation may be used to inducecross-linking. Gamma radiation penetrates relatively deep into thematerial undergoing irradiation, but also increases cross-linking of theinner core. Accordingly, the compression of the core can be adjusted toallow for any increase in hardness that results from the cross-linking.The type of radiation source used will depend in part upon thecomposition of the underlying layers in the golf ball. In addition, thelevel of irradiation will depend upon the desired end properties andcharacteristics of the finished golf ball.

The golf balls of the present invention may be post-processed usingconventional techniques as is customary in the industry. For example,the golf ball cover may first be painted with a composition comprisingwhite or other colored concentrate. Then, indicia (such as a ballnumber, a ball brand name, and/or a company name or logo) can be appliedto the surface of the ball using a pad-printing process. Once the inkindicia have been printed on the ball, a clear protective top-coat iscommonly applied over the print to provide the ball with a shinysurface. The top-coat provides the ball with a smooth, substantiallytack-free surface. A prime coat, typically a film about one-half thethickness of the clear coat, may be applied before production printingor over the production print and before application of the clear coat.

Because compositions of the present invention may be used in any layerof a golf ball, the golf ball construction, physical properties, andresulting performance may vary greatly depending on the layer(s) of theball that include the compositions of this invention. The polyurethane,polyurea, polyurethane-urea, and polyurea-urethane compositions of thepresent invention provide the golf ball with advantageous properties andfeatures. For example, as discussed above, the compositions may be usedto make the outer core, intermediate layer, inner cover, and/or outercover. As discussed above, the molecular weight of the composition mayincrease and the hardness of the ball may increase due to the postcross-linking mechanism, but the resulting ball does not exhibitbrittleness or other undesirable physical properties. Of course, thecross-linking density of the composition also increases during this postcross-linking treatment. That is, the cross-link density of thecomposition that has been further cross-linked by chemical or radiationtreatment is greater than the cross-link density of the startingcomposition. The cover of the ball retains its high impact durabilityand cut/tear-resistance. The ball has high resiliency so that it showsgood flight distance when hit off a tee. At the same time, the ballmaintains a soft “feel” so that its flight path can be controlled onapproach shots near the green. The combination of the core and coverlayer(s) made from a composition of the present invention results in agolf ball having enhanced resiliency and durability characteristicswhile maintaining the desirable feel and playability of the ball.Composition of the present invention can be used to manufacture golfballs having an optimum combination of high resiliency, impactdurability, and soft feel. The combination of the polyurethane,polyurea, polyurethane-urea, or polyurea-urethane and other materialscomprising the core, intermediate layer and/or cover layer provides afinished ball that can be used to achieve increased distance. And yet,the golf ball retains a relatively soft feel and has a good spin rateThus, players can more easily control the play of the ball.

Test Methods

Shore D Hardness measurements are made pursuant to ASTM D-2240“Indentation Hardness of Rubber and Plastic by Means of a Durometer.”Because of the curved surface of the golf ball layer, care must be takento ensure that the golf ball or golf ball subassembly is centered underthe durometer indentor before a surface hardness reading is obtained. Acalibrated digital durometer, capable of reading to 0.1 hardness units,is used for all hardness measurements and is set to take hardnessreadings at 1 second after the maximum reading is obtained. The digitaldurometer must be attached to and its foot made parallel to the base ofan automatic stand. The weight on the durometer and attack rate conformsto ASTM D-2240. It should be understood that there is a fundamentaldifference between “material hardness” and “hardness as measureddirectly on a golf ball.” For purposes of the present invention,material hardness is measured according to ASTM D2240 and generallyinvolves measuring the hardness of a flat “slab” or “button” formed ofthe material. Surface hardness as measured directly on a golf ball (orother spherical surface) typically results in a different hardnessvalue. The difference in “surface hardness” and “material hardness”values is due to several factors including, but not limited to, ballconstruction (that is, core type, number of cores and/or cover layers,and the like); ball (or sphere) diameter; and the material compositionof adjacent layers. It also should be understood that the twomeasurement techniques are not linearly related and, therefore, onehardness value cannot easily be correlated to the other. JIS-C hardnesswas measured according to the test methods JIS K 6301-1975. Shore Chardness was measured according to the test methods D2240-05.

For purposes of the present invention, “compression” refers to Atticompression and is measured according to a known procedure, using anAtti compression device, wherein a piston is used to compress a ballagainst a spring. The travel of the piston is fixed and the deflectionof the spring is measured. The measurement of the deflection of thespring does not begin with its contact with the ball; rather, there isan offset of approximately the first 1.25 mm (0.05 inches) of thespring's deflection. Cores having a very low stiffness will not causethe spring to deflect by more than 1.25 mm and therefore have a zerocompression measurement. The Atti compression tester is designed tomeasure objects having a diameter of 1.680 inches; thus, smallerobjects, such as golf ball cores, must be shimmed to a total height of1.680 inches to obtain an accurate reading. Conversion from Atticompression to Riehle (cores), Riehle (balls), 100 kg deflection, 130-10kg deflection or effective modulus can be carried out according to theformulas given in J. Dalton.

In the present invention, COR is determined according to a knownprocedure, wherein a golf ball or golf ball subassembly (for example, agolf ball core) is fired from an air cannon at two given velocities anda velocity of 125 ft/s is used for the calculations. Ballistic lightscreens are located between the air cannon and steel plate at a fixeddistance to measure ball velocity. As the ball travels toward the steelplate, it activates each light screen and the ball's time period at eachlight screen is measured. This provides an incoming transit time periodwhich is inversely proportional to the ball's incoming velocity. Theball makes impact with the steel plate and rebounds so it passes againthrough the light screens. As the rebounding ball activates each lightscreen, the ball's time period at each screen is measured. This providesan outgoing transit time period which is inversely proportional to theball's outgoing velocity. The COR is then calculates as the ratio of theball's outgoing transit time period to the ball's incoming transit timeperiod (COR=V_(out)/V_(in)=T_(in)/T_(out)).

The preferred standards of measuring the moisture vapor transmissionrate include ASTM F1249-90 entitled “Standard Test Method for WaterVapor Transmission Rate Through Plastic Film and Sheeting Using aModulated Infrared Sensor,” ASTM F372-94 entitled “Standard Test Methodfor Water Vapor Transmission Rate of Flexible Barrier Materials Using anInfrared Detection Technique,” and ASTM D-96 entitled “Water VaporTransmission Rate” among others.

As used herein, the term “about,” used in connection with one or morenumbers or numerical ranges, should be understood to refer to all suchnumbers, including all numbers in a range. It also should be understoodthat when concentrations, amounts, and other numerical data arepresented herein in a range format, they should be interpreted flexiblyto include not only the numerical values explicitly recited as thelimits of the range, but also to include all the individual numericalvalues or sub-ranges encompassed within that range as if each numericalvalue and sub-range is explicitly recited. Furthermore, the inventiondescribed and claimed herein is not to be limited in scope by thespecific embodiments herein disclosed, since these embodiments areintended as illustrations of several aspects of the invention. Anyequivalent embodiments are intended to be within the scope of thisinvention. Indeed, various modifications of the invention in addition tothose shown and described herein will become apparent to those skilledin the art from the foregoing description. Such modifications are alsointended to fall within the scope of the appended claims.

We claim:
 1. A golf ball, comprising: a core having a first Shore Csurface hardness of C₁ in the range of 50 to 90, the core being formedfrom a rubber composition; an intermediate layer surrounding the core,the intermediate layer being formed from a olefin-based acid copolymerionomer composition and having a hardness in the range of 30 to 90 ShoreD; and a cover layer surrounding the intermediate layer having a secondShore C surface hardness of C₂ in the range of 60 to 95, the cover layerbeing formed from a polyurea composition that is produced by a reactionof: i) an isocyanate compound, ii) a moisture-resistant polyamine havinga weight average molecular weight in the range of 500 to 10,000 gramsper mole, and iii) an amine-terminated curing agent, and wherein theratio of C₂ to C₁ is in the range of 0.6 to 1.4, wherein the cover layerhas a moisture vapor transmission rate between 3 grams·mm/m²·day to 4grams·mm/m²·day.
 2. The golf ball of claim 1, wherein themoisture-resistant polyamine is a dimer diamine.
 3. A golf ball,comprising: a core having an inner core and outer core layer, the innercore having a first Shore C surface hardness of C₁ in the range of 50 to90, and the outer core layer having a Shore D surface hardness in therange of about 50 to about 90; an intermediate layer surrounding thecore, the intermediate layer being formed from a olefin-based acidcopolymer ionomer composition and having a hardness in the range of 30to 90 Shore D; and a cover layer surrounding the intermediate layerhaving a second Shore C surface hardness of C₂ in the range of 60 to 95,the cover layer being formed from a polyurea composition that isproduced by a reaction of: i) an isocyanate compound, ii) amoisture-resistant polyamine having a weight average molecular weight inthe range of 500 to 10,000 grams per mole, and iii) an amine-terminatedcuring agent, and wherein the ratio of C₂ to C₁ is in the range of 0.6to 1.4, wherein the cover layer has a moisture vapor transmission ratebetween 3 grams·mm/m²·day to 4 grams·mm/m²·day.
 4. The golf ball ofclaim 3, wherein the moisture-resistant polyamine is a dimer diamine.